Substrate processing method and substrate processing apparatus

ABSTRACT

A substrate processing method for removing a copper oxide film on a surface of Cu and a Cu-containing residue adhered to an interlayer insulating film in a Cu wiring structure on a substrate by using an organic acid-containing gas is provided. The substrate processing method includes removing the Cu-containing residue by etching by supplying the substrate with a processing gas containing an organic acid gas, after the temperature of the substrate is set to be maintained at a first temperature; and removing the copper oxide film on the surface of Cu by means of a reduction reaction by supplying the substrate with the processing gas containing the organic acid gas, after the temperature of the substrate is set to be maintained at a second temperature that is higher than the first temperature.

This application is a Continuation Application of PCT International Application No. PCT/JP2010/051597 filed on Feb. 4, 2010, which designated the United States.

FIELD OF THE INVENTION

The present invention relates to a substrate processing method and a substrate processing apparatus for removing an oxide on a surface of a Cu film and a Cu-containing residue adhered to an interlayer insulating film during formation of Cu wiring.

BACKGROUND OF THE INVENTION

Recently, along with demands for high speed and high integration of semiconductor devices and miniaturization of wiring patterns, it is required to reduce an inter-wiring capacitance and improve conductivity and electromigration resistance of wiring. As a technique therefor, a Cu multilayer interconnection technique attracts attention. In this technique, Cu having a higher conductivity and better electromigration resistance than those of Al or W is used as a wiring material, and an insulating film (low-k film) having a lower dielectric constant than that of SiO₂ is used as an interlayer insulating film.

Cu is easily oxidized, and copper oxide film having high resistance is easily formed on a surface of Cu, which makes it difficult to become a contact. Therefore, an oxide film formed on the surface of Cu has to be removed.

In case of forming a Cu wiring structure by using a damascene method, when an interlayer insulating film is etched, a part of Cu wiring as an underlayer which is exposed through a hole or a via for the wiring is etched, and thus a Cu-containing material is adhered as a residue on the sidewall of the via or the wiring groove. If a next process is performed in a state where the residue is adhered, Cu is diffused into the interlayer insulating film, and this leads to a decrease in a production yield of semiconductor devices. For that reason, the Cu-containing residue needs to be removed.

As for a method for removing an oxide film on a surface of Cu, dry cleaning using a plasma has been used. However, when a plasma is used, Cu as an underlayer may be damaged. Hence, as for a method for dry-cleaning a surface of a substrate without using a plasma, organic acid dry cleaning has been studied (see, e.g., Japanese Patent Application Publication No. 2003-218198).

Moreover, as for a method for removing a Cu-containing residue adhered to an interlayer insulating film, wet cleaning has been used. However, when a low-k film is used as an interlayer insulating film, moisture is absorbed into the low-k film by wet cleaning, which increases a dielectric constant. Accordingly, a method for removing a Cu-containing residue by organic acid dry cleaning has been studied (see, e.g., Enhancing Yield and Reliability by Applying Dry Organic Acid Vapor Cleaning to Copper Contact Via-Bottom for 32-nm Nodes and Beyond (International Interconnect Technology Conference, 2008. p93-p95)).

However, a technique for simultaneously and effectively etching a copper oxide film on a surface of Cu and a Cu-containing residue has not yet been developed.

SUMMARY OF THE INVENTION

In view of the above, the present invention provides a substrate processing method and a substrate processing apparatus capable of effectively removing a copper oxide film on a surface of Cu and a Cu-containing residue adhered to an interlayer insulating film.

The present invention also provides a storage medium storing a program for performing the substrate processing method.

The present inventors have repeated examinations in order to achieve the above goals. As a result, the present inventors have found that when copper oxide is subjected to dry cleaning using an organic acid-containing gas, etching easily occurs at a low temperature and reduction easily occurs at a high temperature. As a result of further examination based on the above information, the present inventors have reached to the following conclusion. That is, a Cu-containing residue adhered to an interlayer insulating film in a Cu wiring structure includes mainly copper oxide and needs to be removed by etching, so that dry cleaning using an organic acid-containing gas is performed at a low temperature at which etching easily occurs. Meanwhile, when a copper oxide film on a surface of Cu is removed by dry cleaning using an organic acid-containing gas, it can be removed by etching or reduction. The reaction conducted at a low temperature has a low reaction speed and requires a longer period of time, whereas the reaction conducted at a high temperature has a high reaction speed. Thus, the copper oxide film on the surface of Cu can be reliably removed within a short period of time by performing reaction that is mainly a reduction process at a high temperature at which a high reaction speed is achieved.

The present invention has been conceived from the above conclusion.

In accordance with first aspect of the present invention, there is provided a substrate processing method for removing a copper oxide film on a surface of Cu and a Cu-containing residue adhered to an interlayer insulating film in a Cu wiring structure on a substrate by using an organic acid-containing gas, the substrate processing method including: removing the Cu-containing residue by etching by supplying the substrate with a processing gas containing an organic acid gas, after the temperature of the substrate is set to be maintained at a first temperature; and removing the copper oxide film on the surface of Cu by means of a reduction reaction by supplying the substrate with the processing gas containing the organic acid gas, after the temperature of the substrate is set to be maintained at a second temperature that is higher than the first temperature.

The interlayer insulating film may be a low-k film. The organic acid may be a carboxylic acid. Preferably, the carboxylic acid may be a formic acid. Further, the first temperature may be within a range from about 100° C. to about 200° C., and the second temperature may be within a range from about 200° C. to about 300° C.

In accordance with second aspect of the present invention, there is provided a substrate processing apparatus for removing a copper oxide film on a surface of Cu and a Cu-containing residue adhered to an interlayer insulating film in a Cu wiring structure on a substrate by using an organic acid-containing gas, the substrate processing apparatus including: a chamber for accommodating a substrate; a mounting table for mounting thereon the substrate in the chamber; a heating mechanism for heating the substrate on the mounting table; a processing gas supply mechanism for supplying a processing gas containing an organic acid gas into the chamber; a gas exhaust mechanism for exhausting an interior of the chamber; and a control mechanism for removing a Cu-containing residue by etching by supplying the substrate with the processing gas containing an organic acid gas after the temperature of the substrate mounted on the mounting table is set to be maintained at a first temperature by the heating mechanism, and then removing a copper oxide film on a surface of Cu by means of a reduction reaction by supplying the substrate with the processing gas containing an organic acid gas after the temperature of the substrate is set to be maintained at a second temperature higher than the first temperature by the heating mechanism.

In accordance with third aspect of the present invention, there is provided a substrate processing apparatus for removing a copper oxide film on a surface of

Cu and a Cu-containing residue adhered to an interlayer insulating film in a Cu wiring structure on a substrate by using an organic acid-containing gas, the substrate processing apparatus including: a chamber for accommodating a substrate; a mounting table for mounting thereon the substrate in the chamber; a heating mechanism for heating the substrate on the mounting table; an energy medium gas supply mechanism for supplying a heated energy medium gas to the substrate on the mounting table; a processing gas supply mechanism for supplying a processing gas containing an organic acid gas into the chamber; a gas exhaust mechanism for exhausting an interior of the chamber; a control mechanism for removing a Cu-containing residue by etching by supplying the substrate with the processing gas containing an organic acid gas after the temperature of the substrate mounted on the mounting table is set to be maintained at a first temperature by the heating mechanism, and then removing a copper oxide film on a surface of Cu by means of a reduction reaction by supplying the substrate with the processing gas containing an organic acid gas after the temperature of the substrate is set to be maintained at a second temperature higher than the first temperature by supplying the heated energy medium gas to the substrate on the mounting table.

In accordance with fourth aspect of the present invention, there is provided a substrate processing apparatus for removing a copper oxide film on a surface of Cu and a Cu-containing residue adhered to an interlayer insulating film in a Cu wiring structure on a substrate by using a processing gas containing an organic acid, the substrate processing apparatus including: a first processing unit, having a mounting table maintained at a temperature for heating the substrate mounted thereon to be maintained at a first temperature, for supplying the processing gas onto the substrate on the mounting table; a second processing unit, having a mounting table maintained at a temperature for heating the substrate mounted thereon to be maintained at a second temperature, for supplying the processing gas onto the substrate on the mounting table; a transfer mechanism for transferring the substrate between the first processing unit and the second processing unit; and a control mechanism for removing a Cu-containing residue by etching by supplying the substrate with the processing gas containing an organic acid gas after the temperature of the substrate mounted on the mounting table of the first processing unit is set to be maintained at the first temperature, and then removing a copper oxide film on a surface of Cu by means of a reduction reaction by supplying a processing gas containing an organic acid gas to the substrate by supplying the substrate with a processing gas containing an organic acid gas after the temperature of the substrate transferred on the mounting table of the second processing unit by the transfer mechanism is set to be maintained at the second temperature.

In accordance with fifth aspect of the present invention, there is provided a A substrate processing apparatus for removing a copper oxide film on a surface of Cu and a Cu-containing residue adhered to an interlayer insulating film in a Cu wiring structure on a substrate by using an organic acid-containing gas, the substrate processing apparatus including: a processing chamber for processing a substrate; a substrate supporting unit for supporting a plurality of substrates in the processing chamber; a heating mechanism for heating the substrates in the processing chamber; a processing gas supply mechanism for supplying a processing gas containing an organic acid gas into the processing chamber; a control mechanism for removing a Cu-containing residue by etching by supplying the substrates with the processing gas containing an organic acid gas after the temperature of the substrates held by the substrate supporting unit in the processing chamber is set to be maintained at a first temperature by the heating mechanism, and then removing a copper oxide film on a surface of Cu by means of a reduction reaction by supplying the substrates with the processing gas containing an organic acid gas after the temperature of the substrates is set to be maintained at a second temperature higher than the first temperature by the heating mechanism.

In accordance with sixth aspect of the present invention, there is provided a non-transitory computer-readable storage medium storing a program for controlling a substrate processing apparatus, wherein the program, when executed by a computer, controls the substrate processing apparatus to perform the substrate processing method described in the first aspect of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view schematically showing an example of a configuration of a substrate processing apparatus for performing a substrate processing method in accordance with a first embodiment of the present invention.

FIG. 2 is a cross sectional view showing an example of a Cu wiring structure to which the present invention is applied.

FIG. 3 is a flowchart showing the method in accordance with the first embodiment of the present invention.

FIG. 4 shows relationship between processing temperature and a decreasing amount of Cu atoms in case of processing Cu₂O by a formic acid.

FIG. 5 is a cross sectional view schematically showing an example of a configuration of a substrate processing apparatus for performing a substrate processing method in accordance with a second embodiment of the present invention.

FIG. 6 is a flowchart showing the film forming method in accordance with the second embodiment of the present invention.

FIG. 7 is a cross sectional view schematically showing an example of a configuration of a substrate processing apparatus for performing a substrate processing method in accordance with a third embodiment of the present invention.

FIG. 8 is a flowchart showing the film forming method in accordance with the third embodiment of the present invention.

FIG. 9 is a cross sectional view schematically showing an example of a configuration of a substrate processing apparatus for performing a substrate processing method in accordance with a fourth embodiment of the present invention.

FIG. 10 is a flowchart showing the film forming method in accordance with the fourth embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, the embodiments of the present invention will be described with reference to the accompanying drawings which form a part hereof.

First Embodiment

(Configuration of a Substrate Processing Apparatus for Performing a Substrate Processing Method in Accordance with the First Embodiment of the Present Invention)

FIG. 1 is a cross sectional view schematically showing an example of a configuration of a substrate processing apparatus for performing a substrate processing method in accordance with the first embodiment of the present invention. Here, the case in which a semiconductor wafer (hereinafter, simply referred to as a “wafer”) is used as a substrate will be described (This is the same in the following embodiments).

This processing apparatus 100 includes a substantially cylindrical airtight chamber 1. Provided on a bottom wall of the chamber 1 is a mounting table 3 for horizontally supporting a wafer W as a semiconductor substrate in the chamber 1.

A heater 4 is buried in the mounting table 3, and a heater power supply 5 is connected to the heater 4. Meanwhile, a thermocouple 6 is provided near the top surface of the mounting table 3, and a signal of the thermocouple 6 is outputted to a heater controller 7. The heater controller 7 is configured to transmit an instruction to the heater power supply 6 in accordance with the signal of the thermocouple 6 and control a wafer W to be maintained at a predetermined temperature by controlling heating of the heater 4. Further, the mounting table 3 is provided with, e.g., three wafer support pins (not shown) for supporting and vertically moving the wafer W. The three wafer support pins can protrude and retract with respect to the surface of the mounting table 3.

A shower head 10 is provided at a ceiling wall la of the chamber 1. A gas inlet port 12 for introducing a gas into the shower head 10 is provided on a top surface of the shower head 10, and a line 21 for supplying a cleaning gas and a purge gas is connected to the gas inlet port 12.

A diffusion space 14 is formed in the shower head 10, and a plurality of injection openings 11 for injecting a processing gas or a purge gas toward the mounting table 3 is formed on a bottom side of the shower head 10. The gas introduced into the shower head 10 through the gas inlet port 12 is diffused in the diffusion space 14, and then is injected through the injection openings 11 in a direction perpendicular to the wafer W mounted on the mounting table 3 in the chamber 1.

A processing gas supply source 22 for supplying a processing gas is connected to the other end of the line 21 connected to the gas inlet port 12. A mass flow controller and valves 24 disposed on both sides thereof are installed in the line 21. A nonreactive gas line 25 is connected to the line 21, and a nonreactive gas supply source 26 is connected to the other end of the nonreactive gas line 25. A mass flow controller 27 and valves 28 disposed on both sides thereof are installed in the nonreactive gas line 25.

As for a processing gas supplied from the processing gas supply source 22, one containing an organic acid gas is used. As for an organic acid forming the processing gas, it is preferable to use a carboxylic acid. The carboxylic acid may be a formic acid (HCOOH), an acetic acid (CH₃COOH), a propionic acid (CH₃CH₂COOH), a butyric acid (CH₃(CH₂)₂COOH), a valeric acid (CH₃(CH₂)₃COOH) or the like. Among them, it is preferable to use a formic acid (HCOOH). In addition, a nonreactive gas supplied from the nonreactive gas supply source 26 is used as a purge gas, a dilution gas, a carrier gas or the like. For example, Ar gas, He gas, N₂ gas or the like can be used therefor.

A gas exhaust port 31 is formed on a bottom wall 1 b of the chamber 1, and a gas exhaust line 32 is connected to the gas exhaust port 31. Further, a gas exhaust unit 33 including a high-speed vacuum pump is provided in the gas exhaust line 32. A conductance variable valve 34 is provided in the gas exhaust line 32 to control a gas exhaust amount from the chamber 1. The gas in the chamber 1 is exhausted by driving the gas exhaust unit 33, and the chamber 1 can be depressurized to a predetermined vacuum level via the gas exhaust line 32.

Installed on a sidewall of the chamber 1 are a loading/unloading port 15 for loading and unloading a wafer

W with respect to a transfer chamber (not shown) close to the substrate processing apparatus 100 and a gate valve 16 for opening and closing the loading/unloading port 15.

The substrate processing apparatus 100 includes a control unit 40, and the control unit 40 has a process controller 41, a user interface 42, and a storage unit 43. The process controller 41 is connected to components of the substrate processing apparatus 100, e.g., the valve, the mass flow controller, the heater controller 7, the gas exhaust unit 33 and the like. These components are controlled by the process controller 41

The user interface 42 is connected to the process controller 41, and includes a keyboard through which an operator inputs a command to manage the processing apparatus, a display for visually displaying the operational states of the plasma processing apparatus, and the like.

The storage unit 43 is connected to the process controller 41, and stores therein control programs to be used in realizing various processes performed by the substrate processing apparatus 100 under the control of the process controller 41, or programs, i.e., recipes, to be used in operating the respective components of the substrate processing apparatus 100 to carry out processes under processing conditions. The processing recipes are stored in a storage medium provided inside the storage unit 43. The storage medium may be a fixed medium such as a hard disk or the like, or a portable device such as a CD-ROM, a DVD, a flash memory or the like. Alternatively, the recipes may be suitably transmitted from other devices via, e.g., a dedicated transmission line.

If necessary, a predetermined processing recipe is read out from the storage unit 43 under the instruction from the user interface 42 and is executed by the process controller 41. Accordingly, a cleaning process is performed in the substrate processing apparatus 100 under the control of the process controller 41.

(Substrate Processing Method of the First Embodiment)

The following is description of the substrate processing method of the present invention which removes a copper oxide film on a surface of Cu and a Cu-containing residue in a Cu wiring structure on a wafer W by using the substrate processing apparatus 100.

Here, as shown in FIG. 2, for example, a wafer W has a structure in which a low-k film 202 as an upper interlayer insulating film is formed on a low-k film 201 as a lower interlayer insulating film via a cap film 206 and a Cu wiring layer 203 is formed on the low-k film 201. A trench 204 and a hole 205 are formed by plasma-etching a portion of the low-k film 202 which corresponds to the Cu wiring layer 203. After ashing of a resist, a Cu-containing residue 209 adhered to the sidewalls of the trench 204 and the hole 205 and a copper oxide film 210 formed on the surface of the Cu wiring layer 203 are removed by dry cleaning using a processing gas containing an organic acid gas.

As can be seen from the flowchart of FIG. 3, first of all, the gate valve 16 is opened, and the wafer W having the Cu wiring structure is loaded into the chamber 1 through the loading/unloading port 15 and then is mounted on the mounting table 3 (step 1). Next, the gate valve 16 is closed, and the temperature of the wafer W is controlled to be maintained at a relatively low first temperature at which etching of copper oxide as a main component of the Cu-containing residue 209 mainly occurs by controlling the heater 4 by the heater controller 7 based on the temperature detection signal outputted by the thermocouple 6 (step 2).

Then, the chamber 1 is exhausted by the vacuum pump of the gas exhaust unit 33. At the same time, the valves 28 are opened to introduce, e.g., Ar gas, from the nonreactive gas supply source 26 into the chamber 1, and the temperature of the wafer W is stabilized to be maintained at the first temperature (step 3).

Next, the valves 24 are opened, and a processing gas containing an organic acid gas is supplied from the processing gas supply source 22 into the chamber 1 via the shower head 10 at a flow rate controlled by the mass flow controller 23, thereby removing mainly the Cu-containing residue 209 by etching (step 4). This step is performed until the Cu-containing residue 209 is almost completely removed by etching. At this time, however, a part of a copper oxide film 210 is also removed by etching.

As described above, as for the organic acid forming the processing gas, it is preferable to use a carboxylic acid such as a formic acid (HCOOH), an acetic acid (CH₃COOH), a propionic acid (CH₃CH₂COOH), a butyric acid (CH₃(CH₂)₂COOH), a valeric acid (CH₃(CH₂)₃COOH) or the like. Among them, it is preferable to use a formic acid (HCOOH). If an organic acid is a carboxylic acid, e.g., a formic acid (HCOOH), the first temperature is preferably set to be within a range from about 100° C. to about 200° C. The etching reaction that occurs when the formic acid is used as an organic acid can be expressed as in the following Eq. (1).

Cu₂O+2HCOOH→2Cu(HCOO)+H₂O  Eq. (1)

Here, Cu(HCOO) is volatile, so that the Cu-containing residue 209 is removed by etching.

The processing gas may be supplied immediately after the wafer W is mounted on the mounting table 3 without performing the stabilization process of step 3. In step 4, the flowing nonreactive gas may be stopped to flow.

After the Cu-containing residue 209 is almost completely removed by the process of step 4, the supply of the processing gas is stopped and the nonreactive gas is supplied. At the same time, the heater 4 is controlled by the heater controller 7 based on the temperature detection signal obtained by the thermocouple 6, and the temperature of the wafer W is controlled to be raised to a second temperature higher than the first temperature at which reduction of copper oxide occurs mainly (step 5).

After the temperature becomes stable, the processing gas containing an organic acid gas is supplied again from the processing gas supply source 22 into the chamber 1 via the shower head 10 at a flow rate controlled by the mass flow controller 23, and the copper oxide film 210 on the surface of the Cu wiring layer 203 is removed by reaction which is mainly a reduction process (step 6). If an organic acid is a carboxylic acid, e.g., a formic acid (HCOOH), the second temperature is preferably in a range from about 200° C. to about 300° C. The reduction reaction that occurs when a formic acid is used as an organic acid can be expressed as in the following Eq. (2).

Cu₂O+HCOOH→2Cu+H₂O+CO₂  Eq. (2)

The processing gas may be supplied before the temperature becomes stable, or may be supplied when the temperature is changed after the completion of step 4. By supplying the processing gas at a temperature lower than the second temperature, the ratio of removing the copper oxide film by etching is increased.

The process of removing the copper oxide film 210 by reaction which is mainly a reduction process is continued until the copper oxide film 210 is completely removed. After the copper oxide film 210 is removed, the supply of the processing gas is stopped, and the nonreactive gas is supplied as a purge gas from the nonreactive gas supply source 26 into the chamber 1 via the shower head 10 at a flow rate controlled by the mass flow controller 27, thereby purging the chamber 1 (step 7). Next, the gate valve 16 is opened, and the wafer W is unloaded from the loading/unloading port 15 (step 8).

In the above-described steps, the Cu-containing residue 209 and the copper oxide film 210 are removed at different temperatures for the following reasons.

FIG. 4 shows a relationship between a temperature of a sample prepared by forming a Cu₂O film having a thickness of about 300 nm on a Si substrate and a decreasing amount of Cu atoms, which is obtained by measuring an intensity of a Cu—Ka radiation by using fluorescent X-ray, wherein the measurement was performed in the case of increasing the temperature of the sample while supplying a formic acid (HCOOH) gas to the sample. As can be seen from FIG. 4, the decreasing amount of Cu atoms increases at a low temperature and becomes maximum at about 200° C. However, the decreasing amount of Cu atoms decreases when the temperature becomes higher than about 200° C. As illustrated in FIG. 4, the etching of Cu₂O mainly occurs at a temperature lower than about 200° C., and the reduction of Cu₂O mainly occurs at a temperature higher than about 200° C.

From the above, it is clear that the Cu-containing residue 209 which needs to be removed by etching can be removed within a relatively short period of time by performing dry etching using an organic acid-containing gas at a relatively low first temperature within a range, e.g., from about 100° C. to about 200° C., at which the etching mainly occurs. Meanwhile, when the copper oxide film 210 is removed by dry cleaning using an organic acid-containing gas, it can be removed by etching or reduction. Generally, the reaction speed decreases at a low temperature and increases at a high temperature. Therefore, it is possible to reliably remove the copper oxide film 210 within a short period of time by performing the reaction which is mainly a reduction process at a second temperature within a range, e.g., from about 200° C. to about 300° C., at which a high reaction speed is obtained. Hence, in the present embodiment, when the Cu-containing residue 209 and the copper oxide film 210 are removed by dry cleaning using an organic acid-containing gas, the Cu-containing residue is removed at the relatively low first temperature by etching, and the copper oxide film on the surface of Cu is removed by reaction which is mainly a reduction process at the second temperature higher than the first temperature. Accordingly, they can be reliably removed within a short period of time.

Further, the substrate processing apparatus 100 of the present embodiment is assembled to a cluster tool-type multi-chamber system having a unit for forming a barrier film such as a Ru film, a Ti film or a Ta film to form Cu wiring at the trench 204 and the via 205 and a unit for forming a Cu seed film. Thus, the removal of the Cu-containing residue 209 and the copper oxide film 210, the formation of the barrier film, and the formation of the Cu seed film can be performed in-situ. Besides, a series of processes from the etching of the low-k film to the formation of the Cu seed film can be performed in-situ by installing in this system a unit for etching the low-k film or ashing a resist.

Second Embodiment

(Configuration of a Film Forming Apparatus for Performing a Film Forming Method in Accordance with a Second Embodiment of the Present Invention)

FIG. 5 is a cross sectional view schematically showing an example of a substrate processing apparatus for performing a substrate processing method in accordance with the second embodiment of the present invention.

This processing apparatus 200 includes a substantially cylindrical airtight chamber 51. A circular opening 52 is formed at a central portion of a bottom wall 51 a of the chamber 51, and a mounting table 53 for horizontally supporting a wafer W in the chamber 51 is provided at the opening 52. An insulating unit 58 is provided between the mounting table 53 and the bottom wall 51 a, and is airtightly coupled to the bottom wall 51 a of the chamber 1.

A heater 54 is buried in the mounting table 53, and a heater power supply 55 is connected to the heater 54. Meanwhile, a thermocouple 56 is provided near a top surface of the mounting table 53, and a signal of the thermocouple 56 is transmitted to the heater controller 57. Further, the heater controller 57 is configured to transmit an instruction to the heater power supply 55 in accordance with the signal of the thermocouple 56, and control the wafer W to be maintained at a predetermined temperature by controlling the heating of the heater 54. Moreover, the mounting table 53 is provided with, e.g., three wafer support pins (not shown) for supporting and vertically moving the wafer W. The three wafer support pins can protrude and retract with respect to the surface of the mounting table 53.

A shower head 60 is provided at a ceiling wall 51 c of the chamber 51. A gas inlet port 62 for introducing a gas into the shower head 10 is provided on a top surface of the shower head 60, and a line 63 for supplying an energy medium gas is connected to the gas inlet port 62.

A diffusion space 64 is formed in the shower head 60, and a plurality of injection openings 61 for injecting an energy medium gas toward the mounting table 53 is formed on a bottom side of the shower head 60. Further, the gas introduced into the shower head 60 through the gas inlet port 62 is diffused in the diffusion space 64, and then is injected through the injection openings 61 in a direction perpendicular to the wafer W mounted on the mounting table 53 in the chamber 51.

Heaters 65 as heating units for heating the energy medium gas in the shower head 60 are provided around the injection openings 61 of the shower head 60. Insulating units 66 made of a material having a low thermal conductivity, e.g., heat-resistance synthetic resin, quartz, ceramic or the like, are provided around the heaters 65 to insulate the heaters 65. Further, an energy medium gas which passes through the heaters 65 is instantly and effectively heated.

An energy medium gas supply source 73 for supplying an energy medium gas is connected to the other end of the line connected to the gas inlet port 62. A mass flow controller 71 and valves 72 disposed on both sides thereof are installed in the line 63. As for the energy medium gas, it is preferable to use a nonreactive gas such as He, Ar, Kr, Xe, N₂ or the like. In addition, an organic acid gas may be used.

A gas inlet port 67 is formed on a sidewall 51 b of the chamber 51, and a line 68 is connected to the gas inlet port 67. The line 68 is branched into a line 68 a and a line 68 b, and a processing gas supply source 76 for performing a cleaning process is connected to one end of the line 68 a. A mass flow controller 74 a and valves 75 a disposed on both sides thereof are installed in the line 68 a. A nonreactive gas supply source 77 for supplying a nonreactive gas is connected to the other end of the line 68 b. A mass flow controller 74 b and valves 75 b disposed on both sides thereof are installed in the line 68 b.

As for a processing gas supplied from the processing gas supply source 76, it is preferable to use one containing an organic acid gas, as in the first embodiment. As for an organic acid gas, it is preferable to use a carboxylic acid. The carboxylic acid may be a formic acid (HCOOH), an acetic acid (CH₃COOH), a propionic acid (CH₃CH₂COOH), a butyric acid (CH₃(CH₂)₂COOH), a valeric acid (CH₃(CH₂)₃COOH) or the like. Among them, it is preferable to use a formic acid (HCOOH).

Meanwhile, a nonreactive gas supplied from the nonreactive gas supply source 77 is used as a carrier gas, a dilution gas and a purge gas for purging a processing gas remaining in a gas phase, a by-product generated in a gas phase by reaction, and an energy medium gas containing a large amount of thermal energy. For example, Ar gas, He gas, N₂ gas or the like can be used.

A gas exhaust port 81 is provided at an opposite side of the gas inlet port 67 provided at the sidewall 51 b of the chamber 51, and a gas exhaust line 82 is connected to the gas exhaust port 81. A gas exhaust unit 83 including a high-speed vacuum pump is provided in the gas exhaust line 82. A conductance variable valve 84 is provided in the gas exhaust line 82, so that a gas exhaust amount from the chamber 51 can be controlled. By driving the gas exhaust unit 83, the gas in the chamber 51 is exhausted, and the chamber 51 can be depressurized via the line 82 to a predetermined vacuum level at a high speed.

A loading/unloading port for loading and unloading a wafer W with respect to a transfer chamber (not shown) close to the processing apparatus 200 and a gate valve for opening and closing the loading/unloading port are installed on the sidewall of the chamber 51 where the gas inlet port 67 and the gas exhaust port 81 are not formed (all not shown).

The processing apparatus 200 includes a control unit 90, and the control unit 90 has a process controller 91, a user interface 92, and a storage unit 93. The process controller 91, the user interface 92, and the storage unit have the same configurations as those of the process controller 41, the user interface 42 and the storage unit 43 of the first embodiment.

(Substrate Processing Method of the Second Embodiment)

The following is description of a substrate processing method of the present embodiment which performs cleaning by removing a copper oxide film on a surface of Cu and a Cu-containing residue adhered to an interlayer insulating film in a Cu wiring structure on a wafer by using the processing apparatus 200.

Here, as in the first embodiment, the Cu-containing residue 209 and the copper oxide film 210 in the structure of FIG. 2 are removed by dry cleaning using an organic acid.

FIG. 6 is a flowchart showing the substrate processing method of the second embodiment. First of all, a gate valve (not shown) is opened, and the wafer W having the Cu wiring structure of FIG. 2 is loaded into the chamber 51 via a loading/unloading port (not shown) and then is mounted on the mounting table 53 (step 11). Next, the gate valve is closed, and the temperature of the wafer W is controlled to be maintained at a relatively low first temperature at which etching of copper oxide as a main component of the Cu-containing residue 209 mainly occurs by controlling the heater 54 by the heater controller 57 based on the temperature detection signal obtained by the thermocouple 56 (step 12).

Then, the chamber 51 is exhausted by the vacuum pump of the gas exhaust unit 83, and the valve 75 b is opened to introduce thereinto, e.g., Ar gas, from the nonreactive gas supply source 77, then the temperature of the wafer W is stabilized to be maintained at the first temperature (step 13).

Thereafter, the valve 75 a is opened to supply a processing gas containing an organic acid gas from the processing gas supply source 76 into the chamber 51 via the gas inlet port 67 at a flow rate controlled by the mass flow controller 74 a, thereby removing mainly the Cu-containing residue 209 by etching (step 14). At this time, the processing gas flows in a horizontal direction indicated by white arrows in FIG. 5. This step is performed until the Cu-containing residue 209 is almost completely removed by etching. At this time, however, a part of the copper oxide film 210 is also removed by etching. As described above, as for the organic acid forming the processing gas, it is preferable to use a carboxylic acid. Especially, it is preferable to use a formic acid (HCOOH). If the organic acid is a carboxylic acid, e.g., a formic acid (HCOOH), the first temperature is preferably within a range from about 100° C. to about 200° C. as in step 4 of the first embodiment, and the reduction reaction occurs as expressed in the Eq. (1).

The processing gas may be supplied immediately after the wafer W is mounted on the mounting table 3 without performing the stabilization process of step 13. In step 14, the flowing nonreactive gas may be stopped to flow.

Next, the supply of the processing gas is stopped by closing the valve 75 a. Then, the valves 72 are opened to introduce an energy medium gas from the energy medium gas supply source 73 into the diffusion space 64 of the shower head 60 via the line 63 and the gas inlet port 62 at a flow rate controlled by the mass flow controller 71. Further, the high-temperature energy medium gas heated by the heaters 65 is injected into the chamber 51 and supplied to the wafer W. The temperature of the wafer W is raised by the thermal energy, and controlled to be maintained at a second temperature higher than the first temperature at which the reduction of copper oxide occurs mainly (step 15). In this case, the energy medium gas is injected in a direction perpendicular to the wafer W as indicated by a black arrow in FIG. 5, so that the temperature of the wafer W can be rapidly raised by the energy medium gas. Accordingly, the temperature of the wafer W can be raised from the first temperature to the second temperature within an extremely shorter period of time compared to that in the first embodiment.

In the case of using a gas other than an organic acid gas, e.g., a nonreactive gas, as an energy medium gas, the supply of the energy medium gas is stopped by closing the valves 72 when the temperature of the wafer W becomes stable at the second temperature. Then, the valves 75 a are opened to supply the processing gas containing an organic acid gas from the processing gas supply source 76 into the chamber 51 via the gas inlet port 67 at a flow rate controlled by the mass flow controller 74 a, thereby removing mainly the copper oxide film 210 on the surface of the Cu wiring layer 203 by the reaction which is mainly a reduction process (step 16). At this time, when the organic acid is a carboxylic acid, e.g., a formic acid (HCOOH), the second temperature falls within a range preferably from about 200° C. to about 300° C., as in step 6 of the first embodiment, and the reduction reaction occurs as described in the Eq. (2).

When the organic acid gas is supplied as an energy medium gas, the copper oxide film 210 is removed by supplying the organic acid gas to the wafer W maintained at the second temperature in step 15.

The process of removing the copper oxide film 210 by reaction which is mainly a reduction process is continued until the copper oxide film 210 is completely removed. After the copper oxide film 210 is removed, the supply of the processing gas is stopped by closing the valves 75 a, and the valves 75 b are opened to supply a nonreactive gas as a purge gas from the nonreactive gas supply source 77 into the chamber 51 via the gas inlet port 67 at a flow rate controlled by the mass flow controller 74 b (step 17). Thereafter, the wafer W is unloaded from the loading/unloading port by opening a gate valve (not shown) (step 18).

In the present embodiment as well as in the first embodiment, when the Cu-containing residue 209 and the copper oxide film 210 are removed by dry cleaning using an organic-containing gas, they can be reliably removed within a short period of time by removing the Cu-containing residue by etching at the relatively low first temperature and removing the copper oxide film on the surface of Cu by reaction which is mainly a reduction process at the second temperature higher than the first temperature.

In the first embodiment, the time for raising the temperature of the wafer from the first temperature to the second temperature is required. Further, when a plurality of wafers is consecutively processed, the time for lowering the temperature of the mounting table from the second temperature to the first temperature is required. On the other hand, in the present embodiment, the high-temperature energy medium gas is injected to the wafer W, so that the temperature of the wafer W can be raised from the first temperature to the second temperature within an extremely short period of time. Hence, the throughput of processing is increased.

As in the case of the substrate processing apparatus 100 of the first embodiment, the substrate processing apparatus 200 of the present embodiment is assembled to a cluster tool-type multi-chamber system including a unit for forming a barrier film such as a Ru film, a Ti film or a Ti film to form Cu wiring at the trench 204 and the via 205 and a unit for forming a Cu seed film. Therefore, the removal of the Cu-containing residue 209 and the copper oxide film 210, the formation of the barrier film, and the formation of the Cu seed film can be performed in-situ. Further, a series of processes from the etching of the low-k film to the formation of the Cu seed film can be performed in-situ by installing at this system a unit for etching the low-k film or ashing a resist.

Third Embodiment

(Configuration of a Film Forming Apparatus for Performing a Film Forming Method in Accordance with a Third Embodiment of the Present Invention)

FIG. 7 is a cross sectional view schematically showing an example of a substrate processing apparatus for performing a substrate processing method in accordance with the third embodiment of the present invention.

This substrate processing apparatus 300 is configured as a cluster tool-type multi-chamber system including a unit for removing a Cu-containing residue, a unit for removing a copper oxide film, a unit for forming a barrier film, and a unit for forming a Cu seed film.

In other words, the substrate processing apparatus 300 includes a Cu-containing residue removal unit 101 for mainly removing a Cu-containing residue, a copper oxide film removal unit 102 for removing a copper oxide film, a barrier film formation unit 103 for forming a barrier film on a sidewall of a via and/or a trench, and a Cu seed film formation unit 104 for forming a Cu seed film on the barrier film. These units 101 to 104 are maintained in a vacuum state and connected to a transfer chamber 105 maintained in a vacuum state via gate valves G. Moreover, load-lock chambers 106 and 107 are connected to the transfer chamber 105 via gate valves G. A loading/unloading chamber 108 in an atmospheric atmosphere is provided at the side of the load-lock chambers 106 and 107 which is opposite to the side where the transfer chamber 105 is provided, and three carrier attachment ports 109, 110 and 111 to which the carriers C capable of accommodating wafers W are attached are provided at the side of the loading/unloading chamber 108 which is opposite to the side where the load-lock chambers 106 and 107 are connected.

Provided in the transfer chamber 105 is a transfer device 112 for loading and unloading a wafer W with respect to the Cu-containing residue removal unit 101, the copper oxide film removal unit 102, the barrier film formation unit 103, the Cu seed film formation unit 104, and the load-lock chambers 106 and 107. The transfer device 112 is disposed at a substantially central portion of the transfer chamber 105, and has at a leading end of a rotatable and extensible/contractible portion 113 two support arms 114 a and 114 b for supporting wafers W. The two support arms 114 a and 114 b are attached to the rotatable and extensible/contractible portion 113 to face the opposite directions.

Installed in the loading/unloading chamber 108 is a transfer device 116 for loading/unloading wafers W with respect to the carriers C and the load-lock chambers 106 and 107. The transfer device 116 has a multi-joint arm structure and can move on a rail 118 in a direction in which the carriers C are arranged, to transfer a wafer W mounted on the support arms 117 provided at the leading end thereof.

This film forming apparatus 300 includes a control unit 120 for controlling each component thereof. The control unit 120 controls each component of the units 101 to 104, the transfer devices 112 and 116, a gas exhaust system (not shown) of the transfer chamber 105, opening and closing of the gate valves G and the like. The control unit 120 has the same configuration as that of the control unit 40 shown in FIG. 1.

The Cu-containing residue removal unit 101 and the copper oxide film removal unit 102 have the same configurations as that of the film forming apparatus of the first embodiment. In the Cu-containing residue removal unit 101, the temperature of the mounting table is set such that the wafer is heated to be maintained at the first temperature within a range, e.g., from about 100° C. to about 200° C. In the copper oxide film removal unit 102, the temperature of the mounting table is set such that the wafer is heated to the second temperature that falls within a range, e.g., from about 200° C. to about 300° C.

(Substrate Processing Method of the Third Embodiment)

The following is description of the substrate processing method of the present embodiment which performs cleaning by removing a copper oxide film on a surface of Cu and a Cu-containing residue in a Cu wiring structure on a wafer W by using the substrate processing apparatus 300 configured as described above.

Here, as in the first embodiment, the Cu-containing residue 209 and the copper oxide film 210 in the structure of FIG. 2 are removed by dry cleaning using an organic acid.

FIG. 8 is a flowchart showing the substrate processing method of the third embodiment. First of all, a wafer W is loaded from a carrier C into one of the load-lock chambers 106 and 107 by a transfer device 116 of the loading/unloading chamber 108 (step 21). Next, the load-lock chamber is exhausted to a vacuum state, and the wafer W is unloaded by the transfer device 112 of the transfer chamber 105. Then, the wafer W is loaded into the Cu-containing residue removal unit 101 and then is mounted on the mounting table (step 22). The temperature of the mounting table is controlled such that the wafer W mounted on the mounting table is set to be maintained at the relatively low first temperature.

In the Cu-containing residue removal unit 101, the temperature of the wafer W is stabilized to be maintained at the first temperature by introducing a nonreactive gas into the chamber (step 23). Then, the processing gas containing an organic acid gas is supplied into the chamber, and the Cu-containing residue 209 is mainly removed at the first temperature by etching (step 24). As described above, as for an organic acid forming the processing gas, it is preferable to use a carboxylic acid. Especially, a formic acid (HCOOH) is preferably used. If an organic acid is a carboxylic acid, e.g., a formic acid (HCCOH), the first temperature falls preferably within a range from about 100° C. to about 200° C. as in step 4 of the first embodiment, and the reduction reaction occurs as expressed in the Eq. (1). This step is executed until the Cu-containing residue 209 is almost completely removed. At this time, a part of the copper oxide film 210 is also removed by etching.

Moreover, the processing gas may be supplied immediately after the wafer W is mounted on the wafer W without performing the stabilization process of step 23. In step 24, the flowing nonreactive gas may be stopped to flow.

After the Cu-containing residue is removed by etching in step 24, the wafer W is unloaded from the Cu-containing residue removal unit 101 by the transfer device 112. Then, the wafer W is loaded into the copper oxide film removal unit 102 and then is mounted on the mounting table (step 25).

The temperature of the mounting table is controlled such that the wafer W mounted thereon is set to be maintained at the second temperature higher than the first temperature.

In the copper oxide film removal unit 102, the temperature of the wafer W is stabilized at the second temperature by introducing the nonreactive gas into the chamber (step 26). Thereafter, the processing gas containing an organic acid gas is supplied into the chamber, and the copper oxide film 210 is removed at the second temperature mainly by reduction (step 27). If the organic acid is a carboxylic acid, e.g., a formic acid (HCOOH), the second temperature is preferably set to be within a range from about 200° C. to about 300° C. as in step 6 of the first embodiment, and the reduction reaction occurs as expressed in the Eq. (2).

The processing gas may be supplied immediately after the wafer W is mounted on the wafer W without performing the stabilization process of step 26. In step 27, the flowing nonreactive gas may be stopped to flow.

The process of removing the copper oxide film 210 by reaction which is mainly a reduction process is continued until the copper oxide film 210 is completely removed. The cleaning process of the present embodiment is completed when the removal process of the copper oxide film 210 is completed. However, in the substrate processing apparatus 300, the wafer W is unloaded via one of the load-lock chambers 106 and 107 after the barrier film formation in the barrier film formation unit 103 and the Cu seed film formation in the Cu seed film formation unit 104 (step 29) are carried out (step 30).

In the present embodiment as well as in the first embodiment, when the Cu-containing residue 209 and the copper oxide film 210 are removed by dry cleaning using an organic-acid gas, the Cu-containing residue is removed at the relatively low first temperature by etching, and copper oxide film is removed at the second temperature higher than the first temperature by reaction which is mainly a reduction process. As a consequence, they can be reliably removed within a short period of time.

As described above, in the first embodiment, the time for raising the temperature of the wafer from the first temperature to the second temperature is required. Further, when a plurality of wafers is consecutively processed, the time for lowering the temperature of the mounting table from the second temperature to the first temperature is required. On the other hand, in the present embodiment, the Cu-containing residue 209 and the copper oxide film 210 are removed by using two units having mounting tables respectively preset to be maintained at the first and the second temperature. Hence, the temperature changing time is not required, and the throughput can be increased by the corresponding amount.

In the cluster tool-type substrate processing apparatus 300 of the present embodiment, a series of processes from the etching of the low-k film to the formation of the Cu seed film can be performed in-situ by providing a unit for etching the Low-k film and ashing a resist.

Fourth Embodiment

(Configuration of a Film Forming Apparatus for Performing a Film Forming Method in Accordance with a Fourth Embodiment of the Present Invention)

FIG. 9 is a cross sectional view schematically showing an example of a substrate processing apparatus for performing a substrate processing method in accordance with the fourth embodiment of the present invention.

This substrate processing apparatus 400 is a batch-type apparatus for heating a plurality of wafers W simultaneously, and includes a substantially cylindrical processing chamber 131 for accommodating and processing a wafer W. A process tube 132 made of quartz and having a double pipe structure is provided in the processing chamber 131, and a cylindrical manifold 136 made of metal is connected to the lower end of the process tube 132. Various lines are connected to the manifold 136.

A wafer boat 133 for holding a plurality of wafers W in the processing chamber 131 is loaded into the process tube 132. The wafer boat 133 is supported by a boat elevator 134 via a thermal insulation container 138, and is loaded and unloaded by vertical movement. A cover 137 is adhered to the boat elevator 134. When the wafer boat 133 is loaded into the process tube 132 by raising the boat elevator 134, the cover 137 covers the lower opening of the manifold 136 in a sealed state. Accordingly, the interior of the process tube 132 becomes a sealed space.

A heater 135 for heating a wafer W is provided in the processing chamber 131 so as to surround the process tube 132. A heater power supply 141 is connected to the heater 135. Meanwhile, a thermocouple 142 is provided near the wafer W mounted on the wafer boat 133, and a signal of the thermocouple 142 is transmitted to the heater controller 143. The heater controller 143 transmits an instruction to the heater power supply 141 in accordance with the signal of the thermocouple 142 and controls the wafer W to be maintained at a predetermined temperature by controlling the heating of the heater 135.

A processing gas line 151 for supplying a processing gas containing an organic acid gas into the process tube 132 is connected to the manifold 136. The processing gas line 151 extends in a horizontal direction toward the inside of the manifold 136, and extends upward such that the processing gas can be supplied toward the upper portion of the process tube 132. A processing gas supply source 152 for supplying a processing gas is connected to the other end of the processing gas line 151. A mass flow controller 153 and valves 154 disposed on both sides thereof are installed in the processing gas line 151. As for an organic acid forming the processing gas, it is preferable to use a carboxylic acid. As for a carboxylic acid, it is preferable to use a formic acid (HCOOH), an acetic acid (CH₃COOH), a propionic acid (CH₃CH₂COOH), a butyric acid (CH₃(CH₂)₂COOH), a valeric acid (CH₃(CH₂)₃COOH) or the like. Among them, it is preferable to use a formic acid (HCOOH).

A nonreactive gas line 161 for supplying a nonreactive gas into the process tube 132 is connected to the manifold 136. The nonreactive gas line 161 extends in a horizontal direction toward the inside of the manifold 136, and extends upward such that the nonreactive gas can be supplied toward the upper portion of the process tube 132. A nonreactive gas supply source 162 for supplying a nonreactive gas is connected to the other end of the nonreactive gas line 161. A mass flow controller 163 and valves 164 disposed on both sides thereof are installed in the processing gas line 161. The nonreactive gas may be used as a purge gas, a dilution gas, a carrier gas or the like. For example, Ar gas, He gas, N₂ gas or the like can be used therefor.

A line 171 is connected to the manifold 136, and a gas is exhausted between an inner line and an outer line of the process tube 132. A gas exhaust unit 172 including a high-speed vacuum pump is provided in the gas exhaust line 171. A conductance variable valve 173 is provided in the gas exhaust line 171, so that a gas exhaust amount from the process tube 132 can be controlled. By driving the gas exhaust unit 172, the gas in the process tube 132 is exhausted, and the process tube 132 can be depressurized via the line 171 to a predetermined vacuum level at a high speed.

The substrate processing apparatus 400 includes a control unit 180 for controlling each component thereof. The control unit 180 has the same configuration as that of the control unit 40 of FIG. 1.

(Substrate Processing Method of the Fourth Embodiment)

The following is description of the substrate processing method of the present embodiment which performs cleaning by removing a copper oxide film on a surface of Cu and a Cu-containing residue adhered to an interlayer insulating film in a Cu wiring structure on the wafer W by using the processing apparatus 400.

Here, as in the first embodiment, the Cu-containing residue 209 and the copper oxide film 210 in the structure of FIG. 2 are removed by dry cleaning using a processing gas containing an organic acid.

FIG. 10 is a flowchart showing the substrate processing method of the fourth embodiment. First of all, the wafer boat 133 accommodating a plurality of, e.g., 100 wafers W, is loaded into the process tube 132 by the boat elevator 134 (step 31). Next, the temperature of the wafer W is controlled to be maintained at a relatively low first temperature at which etching of copper oxide as a main component of the Cu-containing residue 209 mainly occurs by controlling the heater 135 by the heater controller 143 based on the temperature detection signal obtained by the thermocouple 142 (step 32).

Next, the process tube 132 is exhausted by the vacuum pump of the gas exhaust unit 172. Further, the valves 164 are opened to introduce, e.g., Ar gas, from the nonreactive gas supply source 162 into the process tube 132 via the nonreactive gas line 161, thereby stabilizing the temperature of the wafer W at the first temperature (step 33).

Next, the valves 154 are opened to supply a processing gas containing an organic acid from the processing gas supply source 152 into the process tube 132 via the processing gas line 151 at a flow rate controlled by the mass flow controller 153, thereby mainly etching the Cu-containing residue 209 (step 34). This step is executed until the Cu-containing residue 209 is almost completely removed by etching. At this time, however, a part of the copper oxide film 210 is also removed by etching. As described above, as for the organic acid forming the processing gas, it is preferable to use a carboxylic acid. Especially, a formic acid (HCOOH) is preferably used. If an organic acid is a carboxylic acid, e.g., a formic acid (HCOOH), the first temperature is preferably set to be within a range from about 100° C. to about 200° C. as in step 4 of the first embodiment, and the reduction reaction occurs as described in the Eq. (1).

In addition, the processing gas may be supplied immediately after the wafer W is loaded into the process tube 132 without performing the stabilization process of step 33. In step 34, the flowing nonreactive gas may be stopped to flow.

After the Cu-containing residue 209 is almost completely removed by the process of step 34, the supply of the processing gas is stopped, and the nonreactive gas is supplied. The heater 135 is controlled by the heater controller 143 based on the temperature detection signal outputted by the thermocouple 142, and the temperature of the wafer W is controlled to be maintained at the second temperature higher than the first temperature at which etching of copper oxide mainly occurs (step 35).

After the temperature becomes stable, the processing gas containing an organic acid gas is supplied from the processing gas supply source 152 into the process tube 132 via the processing gas line 151 at a flow rate controlled by the mass flow controller 153, and the copper oxide film 210 on the surface of the Cu wiring layer 203 is removed by reaction which is mainly a reduction process (step 36). If an organic acid is a carboxylic acid, e.g., a formic acid (HCOOH), the second temperature is preferably set to be within a range from about 200° C. to about 300° C., and the reduction reaction occurs as described in the Eq. (2).

The process of removing the copper oxide film 210 by reaction which is mainly a reduction process is continued until the copper oxide film 210 is completely removed. After the copper oxide film 210 is removed, the supply of the processing gas is stopped by closing the valves 154, and the valves 164 are opened to supply a nonreactive gas as a purge gas from the nonreactive gas supply source 162 into the process tube 132 via the nonreactive gas line 161 at a flow rate controlled by the mass flow controller 163, thereby purging the process tube 132 (step 37). Thereafter, the pressure in the process tube 132 is returned to an atmospheric pressure, and the wafer boat 133 is unloaded by lowering the boat elevator 134 (step 38).

In the present embodiment as well as in the first embodiment, when the Cu-containing residue 209 and the copper oxide film 210 are removed by dry cleaning using an organic acid-containing gas, the Cu-containing residue is removed at the relatively low first temperature by etching and the copper oxide film on the surface of Cu is removed at the second temperature higher than the first temperature by reaction which is mainly a reduction process. Accordingly, they can be reliably removed within a short period of time.

As described above, in the first embodiment, the time for raising the temperature of the wafer from the first temperature to the second temperature is required. Moreover, when a plurality of wafers is consecutively processed, the time for lowering the temperature of the mounting table from the second temperature to the first temperature is required. In a single-wafer processing environment of the first embodiment, the throughput of processing is decreased by the effect the temperature changing time. However, the present embodiment employs a batch type in which a plurality of, e.g., 100 wafers, is processed simultaneously. Therefore, even though the time for changing the temperature from the first temperature to the second temperature is required, the temperature changing time corresponding to each wafer is not long. Hence, the throughput of processing is hardly decreased.

Another Application of the Present Invention

The present invention can be variously modified without being limited to the above embodiments. For example, the above embodiments have described a case in which only a carboxylic acid represented by a formic acid (HCOOH) is used as an organic acid forming the processing gas. However, it is not limited to the case of supplying only an organic acid gas, and an organic acid gas mixed with another gas such as H₂ or the like may be supplied. Further, an apparatus for performing the substrate processing method of the present invention is not limited to those described in the above embodiments, and various apparatuses can be employed. In addition, the structure of the substrate to be processed is not limited to that shown in FIG. 2, and the substrate to be processed is not limited to a semiconductor wafer. 

1. A substrate processing method for removing a copper oxide film on a surface of Cu and a Cu-containing residue adhered to an interlayer insulating film in a Cu wiring structure on a substrate by using an organic acid-containing gas, the substrate processing method comprising: removing the Cu-containing residue by etching by supplying the substrate with a processing gas containing an organic acid gas, after the temperature of the substrate is set to be maintained at a first temperature; and removing the copper oxide film on the surface of Cu by means of a reduction reaction by supplying the substrate with the processing gas containing the organic acid gas, after the temperature of the substrate is set to be maintained at a second temperature that is higher than the first temperature.
 2. The substrate processing method of claim 1, wherein the interlayer insulating film is a low-k film.
 3. The substrate processing method of claim 1, wherein the organic acid is a carboxylic acid.
 4. The substrate processing method of claim 1, wherein the carboxylic acid is a formic acid.
 5. The substrate processing method of claim 3, wherein the first temperature is within a range from about 100° C. to about 200° C., and the second temperature is within a range from about 200° C. to about 300° C.
 6. The substrate processing method of claim 1, wherein there is used a substrate processing apparatus including a chamber for accommodating a substrate, a mounting table for mounting thereon the substrate in the chamber, a heating mechanism for heating the substrate on the mounting table, a processing gas supply mechanism for supplying the processing gas containing an organic acid gas into the chamber, and a gas exhaust mechanism for exhausting the chamber, wherein the Cu-containing residue is removed by etching after the temperature of the substrate is set to be maintained at the first temperature by the heating mechanism and, then, the copper oxide film on the surface of Cu is removed after the temperature of the substrate is set to be maintained at the second temperature by the heating mechanism.
 7. The substrate processing method of claim 1, wherein there is used a substrate processing apparatus including a chamber for accommodating therein a substrate, a mounting table for mounting thereon the substrate in the chamber, a heating mechanism for heating the substrate on the mounting table, an energy medium gas supply mechanism for supplying a heated energy medium gas to the substrate on the mounting table, a processing gas supply mechanism for supplying the processing gas containing an organic acid gas into the chamber, and a gas exhaust mechanism for exhausting the chamber, wherein the Cu-containing residue is removed by etching after the temperature of the substrate is set to be maintained at the first temperature by the heating mechanism and, then, the copper oxide film on the surface of Cu is removed after the temperature of the substrate is set to be maintained at the second temperature by supplying the heated energy medium gas to the substrate on the mounting table from the energy medium gas supply mechanism.
 8. The substrate processing method of claim 1, wherein there is used a substrate processing apparatus including: a first processing unit, having a mounting table for mounting thereon a substrate and maintained at a temperature for heating the substrate mounted thereon to be maintained at the first temperature, for supplying the processing gas to the substrate on the mounting table; and a second processing unit, having a mounting table for mounting thereon the substrate and maintained at a temperature for heating the substrate mounted thereon to be maintained at the second temperature, for supplying the processing gas to the substrate on the mounting table, wherein the Cu-containing residue is removed by etching after the temperature of the substrate mounted on the mounting table of the first processing unit is set to be maintained at the first temperature and then, the copper oxide film on the surface of Cu is removed after the temperature of the substrate mounted on the mounting table of the second processing unit is set to be maintained at the second temperature.
 9. The substrate processing method of claim 1, wherein there is used a substrate processing apparatus including a processing chamber for processing therein a substrate, a substrate holding unit for holding a plurality of substrates in the processing chamber, a heating mechanism for heating the substrates in the processing chamber, a processing gas supply mechanism for supplying the processing gas containing an organic acid gas into the processing chamber, and a gas exhaust mechanism for exhausting the processing chamber, wherein the Cu-containing residue is removed by etching after the temperature of the substrate supported by the supporting unit in the processing chamber is set to be maintained at the first temperature by the heating mechanism and, then, the copper oxide film on the surface of Cu is removed after the temperature of the substrates is set to be maintained at the second temperature by the heating mechanism.
 10. A substrate processing apparatus for removing a copper oxide film on a surface of Cu and a Cu-containing residue adhered to an interlayer insulating film in a Cu wiring structure on a substrate by using an organic acid-containing gas, the substrate processing apparatus comprising: a chamber for accommodating a substrate; a mounting table for mounting thereon the substrate in the chamber; a heating mechanism for heating the substrate on the mounting table; a processing gas supply mechanism for supplying a processing gas containing an organic acid gas into the chamber; a gas exhaust mechanism for exhausting an interior of the chamber; and a control mechanism for removing a Cu-containing residue by etching by supplying the substrate with the processing gas containing an organic acid gas after the temperature of the substrate mounted on the mounting table is set to be maintained at a first temperature by the heating mechanism, and then removing a copper oxide film on a surface of Cu by means of a reduction reaction by supplying the substrate with the processing gas containing an organic acid gas after the temperature of the substrate is set to be maintained at a second temperature higher than the first temperature by the heating mechanism.
 11. A substrate processing apparatus for removing a copper oxide film on a surface of Cu and a Cu-containing residue adhered to an interlayer insulating film in a Cu wiring structure on a substrate by using an organic acid-containing gas, the substrate processing apparatus comprising: a chamber for accommodating a substrate; a mounting table for mounting thereon the substrate in the chamber; a heating mechanism for heating the substrate on the mounting table; an energy medium gas supply mechanism for supplying a heated energy medium gas to the substrate on the mounting table; a processing gas supply mechanism for supplying a processing gas containing an organic acid gas into the chamber; a gas exhaust mechanism for exhausting an interior of the chamber; a control mechanism for removing a Cu-containing residue by etching by supplying the substrate with the processing gas containing an organic acid gas after the temperature of the substrate mounted on the mounting table is set to be maintained at a first temperature by the heating mechanism, and then removing a copper oxide film on a surface of Cu by means of a reduction reaction by supplying the substrate with the processing gas containing an organic acid gas after the temperature of the substrate is set to be maintained at a second temperature higher than the first temperature by supplying the heated energy medium gas to the substrate on the mounting table.
 12. A substrate processing apparatus for removing a copper oxide film on a surface of Cu and a Cu-containing residue adhered to an interlayer insulating film in a Cu wiring structure on a substrate by using a processing gas containing an organic acid, the substrate processing apparatus comprising: a first processing unit, having a mounting table maintained at a temperature for heating the substrate mounted thereon to be maintained at a first temperature, for supplying the processing gas onto the substrate on the mounting table; a second processing unit, having a mounting table maintained at a temperature for heating the substrate mounted thereon to be maintained at a second temperature, for supplying the processing gas onto the substrate on the mounting table; a transfer mechanism for transferring the substrate between the first processing unit and the second processing unit; and a control mechanism for removing a Cu-containing residue by etching by supplying the substrate with the processing gas containing an organic acid gas after the temperature of the substrate mounted on the mounting table of the first processing unit is set to be maintained at the first temperature, and then removing a copper oxide film on a surface of Cu by means of a reduction reaction by supplying a processing gas containing an organic acid gas to the substrate by supplying the substrate with a processing gas containing an organic acid gas after the temperature of the substrate transferred on the mounting table of the second processing unit by the transfer mechanism is set to be maintained at the second temperature.
 13. A substrate processing apparatus for removing a copper oxide film on a surface of Cu and a Cu-containing residue adhered to an interlayer insulating film in a Cu wiring structure on a substrate by using an organic acid-containing gas, the substrate processing apparatus comprising: a processing chamber for processing a substrate; a substrate supporting unit for supporting a plurality of substrates in the processing chamber; a heating mechanism for heating the substrates in the processing chamber; a processing gas supply mechanism for supplying a processing gas containing an organic acid gas into the processing chamber; a control mechanism for removing a Cu-containing residue by etching by supplying the substrates with the processing gas containing an organic acid gas after the temperature of the substrates held by the substrate supporting unit in the processing chamber is set to be maintained at a first temperature by the heating mechanism, and then removing a copper oxide film on a surface of Cu by means of a reduction reaction by supplying the substrates with the processing gas containing an organic acid gas after the temperature of the substrates is set to be maintained at a second temperature higher than the first temperature by the heating mechanism.
 14. A non-transitory computer-readable storage medium storing a program for controlling a substrate processing apparatus, wherein the program, when executed by a computer, controls the substrate processing apparatus to perform the substrate processing method described in claim
 1. 